Pseudotsuga
About 100 -year-old specimens of Douglas fir ( Pseudotsuga menziesii) in Suhl / Thuringia Forest.
The Douglas fir ( Pseudotsuga ) constitute a genus of flowering plants in the family (Pinaceae ). The trivial name honors the botanist David Douglas Douglas.
- 4.1 Literature
- 4.2 Notes and references
Description
Vegetative characteristics
Pseudotsuga species are evergreen trees. The wood is hard, durable with dark core and resin canals. The bark is smooth in young trees, later reddish- brown and thick. The branches often hanging. The needle-like leaves are arranged opposite one another and individually on branch. The needles have two resin ducts in cross section. You take six to eight years. The seedlings have two to twelve cotyledons ( cotyledons ).
Generative features
Pseudotsuga species are monoecious getrenntgeschlechtig ( monoecious ). The female and male cones sit at one-year branches. The axillary standing male cones are cylindrical. The terminally on short shoots on a 2 to 10 mm long stem bent back to hanging, female cones mature in the same year after fertilization. The egg-shaped or cylindrical pins have many spirally arranged seed scales. The seeds are shed at least a little wider than long. The bracts are long, thin and smooth. They fall like pine cones as whole from the tree. The whitish seeds are 7-12 mm in size from 4 to 14 mm, light to medium brown wings.
Dissemination and paleobotany
The genus Pseudotsuga includes four species in western North America, in China and Japan.
The genus Pseudotsuga was home to the last Ice Age in Europe. During the ice ages, the European representative of the genus, however, are extinct.
The European far the best known species in the genus is the Douglas Fir ( Pseudotsuga menziesii).
System
The botanical genus name Pseudotsuga is derived from the Greek word pseudos wrong and Tsuga from.
In the genus Douglas fir (Pseudotsuga) there are four kinds and some varieties:
- Japanese Douglas Fir ( Pseudotsuga japonica ( Shiras. ) Bite. ), Origin: Japan
- Großzapfige Douglas Fir ( Pseudotsuga macrocarpa ( Vasey ) Mayr ), Origin: southwestern California
- Douglas Fir ( Pseudotsuga menziesii ( Mirb. ) Franco), Origin: Western North America. There are two varieties: Called coastal Douglas fir, Douglas fir and Ordinary or Green Douglas Fir ( Pseudotsuga menziesii var menziesii), Origin: Canada, United States
- Mountain Douglas fir, also called Blue Douglas Fir ( Pseudotsuga menziesii var glauca ( Beissn. ) Franco), Origin: Canada, USA, Mexico
- Pseudotsuga sinensis var sinensis, Origin: China.
- Pseudotsuga sinensis var brevifolia (WC Cheng & LK Fu ) Farjon & Silba: Is located in the Chinese provinces of Guizhou and southwest Guangxi, typically grows on south-facing slopes and mountain peaks, on calcareous rocky soils at altitudes of about 1300 meters.
- Pseudotsuga sinensis var gaussenii ( flous ) Silba: Is located in the Chinese provinces: Jingxi, Sichuan and Zhejiang; is expected by some authors for variety brevifolia.